Air-compressor



(No Model.) 3 Sheets-Sheet 1. E HILL AIR COMPRESSOR.

Patented June 23,1891.

(No Model.) 3 Sheets-Sheet 2.

E. HILL.

AIR COMPRESSOR.

Patented June 23, 1 891.

(N 3 Sheets-Sheet 3.

E. HILL. AIR COMPRESSOR.

No. 454,590. Patented June 23,1891.

1m: humus warms co., "(mo-mum, wnsmnorun, n c.

UNITED STATES PATENT OFFICE.

E SENEZER HILL, OF SOUTH NOR\VALK, CONNEC ICUT.

AIR-COMPRESSOR.

S?ECIFICATION forming part of Letters Patent No. 454,590, dated June 23,1891. Application filed May 24,1889. Serial No. 311,993. (No model.)

To all whom it may concern.-

Be it known that I, EBENEZER HILL, of South Norwalk, in the county ofFairfield and State of Connecticut, have invented a new Improvement inAir-Compressors; and I do hereby declare the following, when taken inconnection with accompanying drawings and the letters of referencemarked thereon, to be a full, clear, and exact description of the same,and which said drawings constitute part of this specification, andrepresent, in

Figure 1, a side view of so much of the cylinder as necessary toillustrate the valve-gear for one outlet-valve; Fi 2, a vertical sectioncutting through the outlet-valve at right angles, showing the valve inthe open position; Fig. 3, the same as Fig. 2, showing the valve in theclosed position; Figs. 4, 5, 0, and 7, detached views of the valve andeccentric crankarms, showing the connectingcylinder in vertical centralsection and in diiterent positions to illustrate the operation; Figs. 8,9, 10 and 11, modifications in the adaptation of the vacuum cylinder andpiston; Fig. 12, a modification in the adaptation of the air-cushion.

This invention relates to an improvement in that class ofair-compressors in which the Valves are mechanically operated for theescape of compressed air from the cylinder. Under the more generalconstruction of this class of air-compressors the valves are set so asto open at a predetermined point in the movement of the piston, and thispoint is intended to be when the pressure in the cylinder shall havereached the pressure in the receiver. For illustration, suppose thepressure outside the valve in the receiver, or whatever it may be, isfifteen pounds, that pressure under ordinary circumstances will beattained in the cylinder when the piston has reached its half-stroke inthe cylinder. Now it under this positive arrangement of the valves withrelation to the piston it be desired to reduce the pressure in thereceiver or outside the valve-say to ten pounds-the continued action ofthe machine will still compress the air to the same extent in thecylinder and discharge it under a pressure of fifteen pounds, becausethe valve would not ordinarily open until the time when that pressure offifteen pounds in the cylinder had been attained. On the contrary, if itbe desired to increase the pressure in the receiver, the valve will openbefore the receiver-pressure has been reached in the cylinder. In thefirst case the valve is opened too late and in the latter case openedtoo early. The results of thus opening the valve are too well known torequire particular description. Hence when such change in the pressureis desired a corresponding resetting of the valve is necessary to aperfect working of the machine.

In another application, Serial No. 304,622, I have describedimprovements in valve-operating mechanism to overcome the diflicultiesreferred to, and which invention consists in providing an overmotion ofthe parts with which the outlet-valves are mechanically engaged andthrough which the power is applied to the said valves, during whichovermotion the outlet-valves are independent of the power combined withmeans independent of such power, which during such overmotion mayoperate upon the outlet-valves to automatically open the same when theyare brought to an equilibrium by the pressu re in the cylinder, on thecylinder side of the valve, substantially equaling the pressure on theout or receiver side of the valves, the valves being held to their seatsby the press ure of the air in the receiver or on the back of the valve.In that invention the outletvalves are positively closed by the actionof the eccentric; but on the return operation of the eccentric the valveis left free and independent of the eccentric until a predeterminedpressure shall have been attained within the cylinder, when an auxiliarypower is automatically applied to the valve to throw it instantlyto itswide-open position, and this irrespective of what may be the position ofthe piston in the cylinder. The auxiliary power described in thatapplication as the means for thus opening the valve is a spring or aweight.

The object of my present invention is to employ a vacuum as the meansfor bringing atmospheric pressure to operate as the said auxiliarypower.

As the outlet-valve necessarily remains stationary after it is closed atthe end of the advancing stroke of the piston until the piston hasreturned to the opposite end of the cylinder and again advanced towardthat "alve until the equilibrium pressure has been produced the time ofrest is so great that if an ordinary stationary vacuum dash-pot be usedto operate the valve the vacuum would necessarily be produced asthevalve reached its.

closed position, and that vacuum must be held through the long space oftime mentioned. To hold the vacuum active for this long time would bedifficult, because of the liability of air to leak into thevacuum-cylinder and destroy its efficiency.

By my present invention I am enabled to produce the vacuum by whichatmospheric pressure isbrought to bear as the power to open theoutlet-valve and immediately before the time of opening of the valveoccurs; and the invention consists in combining with the valve which isarranged to open and close the outlet-passage from thecompressing-cylinder a cylinder and piston interposed between the saidvalve and the motor by which the valve is positively closed, and so thatthe piston will be drawn from the cylinder by the said motor whenreturning from the closing movement to produce a vacuum in saidcylinder, which vacuum will at the proper time permit the atmosphericpressure thereby produced to operate as the power to move the valve fromthe closed to the open position, and as more fully hereinafterdescribed.

In illustrating the invention I represent it as applied to rotary oroscillating valves.

A represents the outlet-valve spindle. B,

7 Figs. 2land 3, represents the outlet-valve; O,

the port leading from the cylinder to the outlet-valve, the position ofthe valve in Fig. 2 being open and the position in Fig. 3 being closed.The valve thus illustrated is the same as that in the application beforereto move in the cylinder.

ferred to.

To the valve-spindle A a crank-arm D is made fast, by which theoscillating movement may be imparted to the spindle to give to the valveits opening and closing movement.

E is a second crank-arm hung upon an axis F, and with which arm theeccentric-rod Gis connected, so that through the operation of theeccentric a vibratory movement will be imparted to the crank-arm E, thecrank-arms D and E being arranged in substantially the same plane.Connection is made between the crank-arms D and E, so that vibratorymovement imparted to the crank-arm E may under certain circumstances becommunicated to the crank-arm D. The connection between the crank-arms Dand E is a cylinder ll closed at one end, and hung by that end to one ofthe arms, as E, upon a crank-pin I, combined with a piston J, the rod Kof which extends through the other end of the cylinder, and is hung upona crank-pin L on the other crank-arm D. (See Fig. 4.) The piston is freeThe closed end of the cylinder is tight, and so that if the piston bewithdrawn from the closed end of the cylinder it will create a vacuumtherein, which vacuum causes a corresponding atmospheric pressure uponthe opposite side of thpiston, and which pressure, if free to operate,will cause the piston to return to the closed end of the cylinder.

The position of the outlet-valve crank-arm D in Fig. 4 is as when thevalve is in its closed position and at the closing extreme throw of theeccentric. From this point the movement of the eccentric crank-arm E isin the direction indicated by the arrow,.Fig. 4. The crank-pin I of theeccentric-rod E, it will be observed, is out of line with the crankpinof the valve-arm and the axis upon which the eccentric crank-arm. turns.As the eccentric moves as indicated by the arrow, Fig. 4, it will takethe crank-pin of the eccentric-arm across and to the other side of theline between the crank-pin of the valve crank-arm and the axis uponwhich the eccentric-crank turns to the position seen in Fig. 5. In thispart of the movement of the eccentric-arm no substantial movement hasbeen imparted to the valve crank-arm. The outlet-valve therefore stillremains closed, and this position is attained when the piston hasarrived at the end of its stroke opposite this valve. The piston nowreturns, the eccentric continuing its movement; but from this point,Fig. 5, the movement of the crank-pin of the eccentricarm is away fromthe crank-pin of the valvearm, so that the valve being held to its seatby the pressure upon its back the cylinder will be drawn from theposition seen in Fig. 5 to that seen in Fig. 6, the piston being held bythe pressure upon the valve. This will accordingly lengthen theconnection between the two crank-pins to the extent of the movement ofthe cylinder, and in so drawing the cylinder from the piston a vacuumwill have been created in the cylinder with a corresponding atmosphericpressure upon the reverse side of the piston, the tendency of which isto force the piston into the cylinder. This vacuum and consequentatmospheric pressure will continue in force until the pressure withinthe cylinder upon the face of the valve substantially counterbalancesthe pressure upon the back of the valve. Then the said atmosphericpressure comes into opera-' they will move together to the otherextreme,

as seen in Fig. 4, when the valve will have reached its extreme closedposition, and thus have made one complete opening and closing movement.It will thus be seen that the vacuum is not created until the time it isactually required, and being emploped substantially as soon as it iscreated there is no opportunity to destroy or reduce that vacuum ITO bythe leakage of air into the vacuum, as is unavoidably the case in avacuum dash-pot.

As the valve when in equilibrium, as I have described, will require buta slight power to move it, there would naturally be a thump as thepiston returns into the cylinder under the action of the saidatmospheric pressure. To avoid this thumping or jar, I provide acushion, and this I do by extending the cylinder toward the arm to whichthe piston-rod is connected and introducing a stationary head M into thecylinder distant from the closed head sufficient to permit thevacuum-piston to operate. The piston-rod works through this head M, andthe vacuum-cylin der is constructed with air-openings N near the head Mto permit the escape of air as the piston is drawn away from the closedend of the cylinder. Into the extension of the cylinder, as at O, asecond piston I is formed upon or attached to the pistonrod, which fitsclose into its cylinder and moves with the piston-rod and thevacuumpiston, and. so that as the piston and cylinder separate, as seenin Fig. 6, the piston P will be drawn from its head M and will take airinto the cylinder through a small aperture R provided for the purpose,and the air thus taken in will form aeushion upon which the piston Iwill strike as it returns with the Vacuum-piston J, the air of thecushion grad ually escaping, so as to permit the vacuumpiston to reachits normal position without thump or jar.

Instead of employing the crank-arm E between the cylinder and theeccentric-rod,the connection may be made directly to the eccentric-rod,as represented in Figs. 8 and 9, Fig. 8 representing the position of theparts when the valve is closed and substantially the same as Fig. 4,before referred to. In this case the cylinder is represented as hungdirectly to the eccentric-rod, and so as to move with it, while thepiston-rod is connected to the valve-crank, as in the firstillustration.The dead-point in the movement of the eccentric gives substantially thesame rest after the valve has reached its closed position, as I havedescribed in the first illustration. Fig. 9 represents the same parts asFig. 8 in the same relative position as that represented in Fig. 6-thatis, when the vacuum has been substantially formed and so that as theeccentric completes its stroke the vacuum will be brought into actionand produce the opening movement of the valve, as before described.

The moving vacuum-cylinder may be employed with. a slide-valve, asrepresented in Fig. 10, the cylinder being connected directly to theeccentric-rod, and the piston-rod to the valve-rod, as indicated in thatfigure, and so that the operation of the eccentric upon the cylinder andpiston to form the vacuum will be the same as that described withreference to Figs. 8 and 9.

In some cases it may be desirable to mechanically hold the valve in theclosed position and give to it the quick opening action which willnecessarily follow the operation of the atmospheric pressure. In suchcase a latch maybe provided to catch the valve-arm when in the closedposition, as represented in Fig. 11, in which a represents a latch whichwill engage the crank-arm of the valve when it has reached its closedposition, and this latch will be tripped at the proper time by anysuitable means, as by engaging a projection on the red, as seen inbroken lines, Fig. 11, and so that at a predetermined point after thevacuum is formed the valve will be released. \Vhile therefore preferringthe arrangement of the cylinder and piston as first described, I do notwish to be understood as limiting the invention to any particulararrangement of the vacuum piston and cylin der further than that theyshall be so arranged that the vacuum is produced by the movement of thevalve-motor immediately before the opening movement of the valve isrequired.

I have represented the piston as hung to the valve-arm and the cylinderas hung to the eccentric-arm; but it will be understood that this ordermay be reversed without change in the result or departure from thisinvention.

While I prefer to make the air-cushion as a part of the vacuum-cylinderand a piston on the same red as the vacuum-piston, the com bination ofthe air-cushion with the vacuum may be otherwise arranged.Forillustration, the air-cushion cylinder may be a separate andindependent cylinder with corresponding independent piston, asrepresented in Fig. 12, the same letters as heretofore used indicatingcorresponding parts in this figure.

It will be understood that the term eccentric as applied to the motor bywhich the valve is operated is to be used in the general sense asincluding any motor by which the valve is operated.

I do not in this application claim, broadly, the outlet-valve heldsolely by friction until the equilibrium pressure is produced thereonwith an auxiliary power to operate the valve, as that is the subject ofanother application, Serial No. 304,622.

I claim- 1. In an air-compressor having a valve arranged to open andclose the outlet-passage from the comprcssing-cylinder and a motoroperating to close the valve, the combination therewith of a cylinderand a piston in said cylinder, said cylinder and piston being interposedbetween the said valve and the said motor, substantially as described,and whereby as the motor returns after the closing of the valve thereturn movement will draw the piston from the cylinder and produce avacuum with corresponding atmospheric pressure which will operate toimpart to the valve its opening movement.

In an air-compressor having a valve arranged to open and close theoutlet-passage TIO from the compressing-cylinder and a motor operatingto close the valve, the combination therewith of a. cylinder and apiston in said cylinder, said cylinder and piston being interposedbetween the said valve and thesaid motor, and an air-cushion, composedof acylinder and piston, also interposedbetween the valve and its motor,substantially as and for the purpose described.

3. In an air-compressor having a valve arranged to open and close theoutlet-passage from the compressing-cylinder and a motor operating toclose the valve, the combination therewith of a cylinder and a piston insaid cylinder, said cylinder and piston being interposed between thesaid valve and the said motor, the said cylinder being extended towardthe point of its piston connection and the piston-rod provided with asecond piston in said extension and the cylinder being constructed witha stationary head between the said two pistons, the said extension andits piston forming an air-cushion, substantially as and for the purposedescribed.

4:. In an air-compressor having a valve arranged to open and close theoutlet-passage from the compressing-cylinder, the back of the valveexposed to the pressure of the air in the receiver and the face of thevalve being exposed to the pressure from the cylinder, and whereby thesaid valve will be frictionally held substantially stationary upon itsseat by the said pressure upon its back until the pressure upon the faceof the valve substantially equals the pressure upon the back of thevalve, avibrating crank-arm in connection with said valve and by whichit is operated, a second vibrating crank-arm in connection with themotor, a cylinder closed at one end, hung by said closed end to one ofsaid crank-arms, a piston in said cylinder, the piston-rod extendingfromjthe piston and hung to the other crank-arm, and so that as the saidcrank-arms separate the piston will be drawn from the cylinder andproduce a vacuum therein, substantially as and for the purposedescribed.-

5. In an air-compressor having a valve arranged to open and close theoutletpassage from the compressing-cylinder, the back of the valveexposed to the pressure of the air in the receiver and the face of thevalve being exposed to the pressure from the cylinder, and whereby thesaid valve will be friction ally held substantially stationary upon itsseat by the said pressure upon its back until the pressure upon the faceof the valve substantially equals the pressure upon the back of thevalve,avibratingcrank-arm in connection with said valve and by which itis operated, a second vibrating crank-arm in connection with the motor,a cylinder closed at one end, hung by said closed end to one of saidcrank-arms, a piston in said cylinder, the piston-rod extending from thepiston and hung to the other crank-arm and so that as the saidcrank-arms separate the piston will be drawn from the cylinder andproduce a vacuum therein, the said cylinder extended toward the arm towhich the piston is connected and the piston-rod being provided with asecond piston in the said extension of the cylinder, the said cylinderconstructed with a stationary head between the said two pistons, thesaid extension and its piston forming an aircushion, substantially asand for the purpose described.

EBENEZER HILL.

Witnesses:

JOHN A. SLATER, CHAS. J. HILL.

